Buffer Map (Point, Line & Polygon Buffers)
Create geometric buffer zones around points, lines, and polygons with multi-distance overlays, area calculations, and GeoJSON export.
The Buffer Map tool generates multi-distance geometric buffer zones around points, paths, and polygon features on an interactive map. It calculates total enclosed buffer surface area, handles overlapping buffer unions, and exports clean vector layers to GeoJSON and KML.
Buffer Map Technical Specifications & Standards
WGS84 (EPSG:4326)
Standard global ellipsoidal coordinate reference system
Turf.js Geodesics
Millimeter precision with smooth 64-step circular joins
GeoJSON · KML · CSV · SVG
Compatible with QGIS, ArcGIS, Google Earth & CAD
100% Client-Side
Calculations run in-browser. Zero coordinate logging.
How to Use the Buffer Map (Point, Line & Polygon Buffers)
Follow this step-by-step procedure to execute precise spatial measurements and export results.
- 1Choose feature type: Select Point, Line, or Polygon geometry.
- 2Plot geometry on map: Click anywhere on the interactive map to place vertices.
- 3Adjust buffer distance: Set buffer radius in meters, kilometers, feet, or miles.
- 4Export buffered vector: Download the resulting buffer boundary geometry as a GeoJSON file.
Geodesic Precision vs. Competitor Mapping Approaches
Most legacy mapping utilities (such as CalcMaps and FreeMapTools) rely on planar Web Mercator projections or spherical approximations, causing significant mathematical distortion at higher latitudes. GeoMap Suite computes exact ellipsoidal geodesics on the WGS84 reference ellipsoid.
| Calculation Model | Mathematical Basis | Distortion on WGS84 | Standard Tools | Practical Application |
|---|---|---|---|---|
| Planar (Web Mercator) | Cartesian dx² + dy² | 10% to 200%+ error | CalcMaps / Simple map tools | Distorts drastically away from equator. Inaccurate for true distance. |
| Spherical Great-Circle | Haversine (R = 6,371 km) | Up to 0.5% (~5 km/1,000 km) | Basic Google Maps wrappers | Ignores Earth's polar flattening. Reasonable for rough estimates. |
| GeoMap Suite Ellipsoidal | Karney Direct/Inverse WGS84 | < 15 nanometers (<0.0001%) | GeoMap Suite | Geodetic surveying, maritime, flight paths & legal boundary analysis. |
Worked Example: 500-Meter Environmental Stream Buffer
An environmental consultant calculates the protected riparian conservation zone around a 2-mile river segment.
Input Parameters
- Feature
- 3-point river centerline
- Buffer Distance
- 500 meters (0.5 km)
Computed Outputs
- Buffer Area
- 588.1 acres
- Square Kilometers
- 2.38 km²
- Export Format
- GeoJSON Polygon
Step-by-Step Mathematical Process
- Compute Minkowski sum offset along line string segments.
- Round end-caps with circular arcs.
- Union overlapping buffer polygons into a single continuous polygon.
- Evaluate total buffered area: 2.38 sq km (588 acres).
Understanding Your Results & Practical Interpretation
Line Buffers vs. Point Buffers
A point buffer creates a perfect circle. A line buffer offsets each segment perpendicularly and connects vertices with rounded caps or miters.
Practical Applications & Real-World Use Cases
Zoning and Setback Compliance
Ensure new construction satisfies 100-foot wetland setback restrictions.
Noise Exposure Contours
Model sound buffers around highway corridors or airport runways.
Mathematical Methodology & Geodetic Accuracy
Turf.js Geodesic Buffer Generation (JTS / GEOS algorithms)
Uses constructive solid geometry algorithms to compute the morphological dilation of input vector geometries on a sphere.
Buffer(G, d) = { p | min_{q ∈ G} dist(p, q) ≤ d }Limitations & Boundary Conditions
- •Large buffer distances (> 1,000 km) will exhibit map projection distortion if visualized on Web Mercator without geodesic tessellation.
Authoritative Reference Standards
Troubleshooting & Geographic Edge Cases
Why are the line buffer ends rounded?
Standard GIS buffering applies round end-caps to ensure every point along the perimeter is exactly equidistant from the line ends.
Frequently Asked Questions
A buffer is a proximity zone created around a geographic point, line, or polygon at a specified setback distance (e.g., a 100-meter environmental river buffer or a 5-mile retail service radius).